Serial section photography of organic material

ABSTRACT

Successive sections are taken from animal or botanical material embedded in a supporting block. The block is then indexed rotatably step by step. In the several indexed positions of the block, the work surface from which the section has been removed is washed and stained and photographed and the block is advanced radially toward the knife for further sectioning and for staining and photographing each newly exposed surface. In each cycle the block is raised for indexing and lowered to engage matched face splines for precision registration with the camera. Preferably automatic exposure of a small predetermined number of frames of motion picture film follows each sectioning and staining of the work, whereby the resulting film not only records the successive exposed surfaces but may be projected to give the impression that the observer is actually moving through the work, thus permitting the investigator to trace selected elements (vascularity, neural bundles, anatomical structure, etc.) through an organ or other specimen while maintaining visual positional reference to other anatomical features.

United States Patent Ahrens et al.

[ 5] Mar. 14, 1972 [54] SERIAL SECTION PHOTOGRAPHY OF ORGANIC MATERIALPrimary ExaminerLouis R. Prince Assistant Examiner-Joseph W. Roskos [72]Inventors: Robert H. Ahrens, Milwaukee; John A. A wh fl g wh l Bartlett,Pewaukee; James S. Roberts, Brookfield; Pieter W. Schipper, Elm 57ABSTRACT Grove, all of Wis.; Roy Mills, Cardiff, m Successive sectionsare taken from animal or botanical material embedded in a supportingblock. The block is then indexed [73] AsS'gnee: Milwaukee & Companyrotatably step by step. ln the several indexed positions of the Inc.,Milwaukee, Wis. block, the work surface from which the section has been[22] Filed: No 13 1969 removed is washed and stained and photographedand the block is advanced radially toward the knife for further section-PP 876,329 ing and for staining and photographing each newly exposedsurface. In each cycle the block is raised for indexing and 52 US. Cl..3s2/s4, 35/20, 35/51, W engage matched face Splines Precisim 83/567118/315 352/131 t1on with the camera. Preferably automatic exposure of asm pre etermme num ro rameso motion picture Im 511 Int. Cl. ..G03b41/00d d be ff f n [58] Field of Search 352/84 131 83/915 5 follows eachsectioning and staining of the work, whereby the 83/567 f 35/20resulting film not only records the successive exposed surfaces but maybe projected to give the impression that the observer [56] ReferencesCited is actually moving through the work, thus permitting theinvestigator to trace selected elements (vascularity, neural bun- UNITEDSTATES PATENTS dles, anatomical structure, etc.) through an organ orother specimen while maintaining visual positional reference to2,444,729 7/1948 Crockwell... .....352/39 other anatomical features2,614,454 10/1952 Steffen ..352/39 3,459,079 8/1969 DeGain ..83/267 X 11Claims, 27 Drawing Figures 2 5 -1 L Wilma, i Q

b i Rmsra STEM...

(OPTlONAL) :c sn A MOVIE Canaan Patented Mar c h14, 1972 1 3,649,108

9 Sheets-Sheet 5 04 v E NTOR$ Passer A. Hilts/vs, Jay/v fl- Earner.Jnmss .5. (eraser: Pug-r5: W 561/0 24)? Rav MILL A1 TO RNEIS PatentedMarch 14, 1972 9 Sheets-Sheet '7 s 2 m E V m ZI0/ 202 202 ZO/ MIMI" MM!"INVBNTOR5 /?D8E27'H. 1 2/125,, Jahw 9. fink/u n", James 1 F0552 r5,9/2722 n4 imp/ 52 Fay M/Lz. 5

BY km, 42.2,

hurrah ATTORNEY,

SERIAL SECTION PHOTOGRAPHY OF ORGANIC MATERIAL BACKGROUND OF INVENTIONThe desirability of photographing serial sections of a specimen inmotion picture format has been recognized for many years. Efforts toaccomplish this can be traced back to the early part of this century.These efforts were rewarded with marginal success because of thedifficulties involved with aligning the individual stained sections (orslides) in precision registration with the camera.

Dr. Samuel Postlethwait, of the Dept. of Biological Sciences, and RoyMills of the Audio Visual Center, Purdue University, conceived ofphotographing the block face from which the section had been cut,instead of photographing the section itself.

The feasibility of photographing the block face has since beendemonstrated. The improvements herein disclosed and claimed have to dowith facilitating this operation and making it practicable foreducational and other uses. In referring to photographing of the blockface, it is intended in this application to include any means ofreproduction, including, for example, a television camera and, ifdesired, the magnetic tape recording of the output of the televisioncamera.

SUMMARY OF INVENTION The apparatus herein disclosed combines features ofa large scale high precision microtome and the staining functions of ahistology laboratory, and a photograph stand and controlling apparatusfor automating and preprogramming the operation. The apparatus is uniquein this field in its use of a rotary indexing table. This gives maximumspacing between stations in a relatively compact overall organization.

After conventional processing (i.e., fixing, dehydrating, clearing, andinfiltrating) the desired specimen is normally embedded in a block ofsuitable supporting material such as paraffin, nitrocellulose orpolyethylene glycol. A camera or cameras for routine photography,television, or other forms of reproduction have precision adjustmentwith respect to the block, and means is provided for cyclic relativeindexing rotary movement to expose the work for sectioning and to makeits cut face accessible for staining and washing. It is preferably thework rather than the camera which is indexed or otherwise moved out ofthe way for this purpose in the instant exemplification, although theconverse is practicable.

Retractable inverted hood means is withdrawn during the intermittentoperation of sectioning, and during photography, and is advanced toconfine the various stains and washes and rinses which may be directedat the face of the work exposed by the sectioning operation, the stainsbeing conventionally used to identify or emphasize features to bestudied. Means is provided for catching staining and rinsing liquids.The staining liquids are preferably, though not necessarily, returned totheir containers, from which they are then recirculated. The surplusrinses will normally be discharged through a drain. The staining nozzlesand rinsing nozzles may be adjusted to function in any desired positionor positions of indexed movement.

To permit such movement and accurately to restore the predeterminedrelative position of the parts, matched face splines with mating teethare provided between the indexing table and the support and between thetable and the indexing rack. A ram lifts the table preliminary to eachindexing operation, whereby to disengage said teeth and to permit theactuation and return of the rack. While it is the freshly cut surface ofthe specimen which is preferably photographed by one or more cameras,arrangements permit the severed sections (2 to 100 microns in thickness)either to be discarded or to be collected and preserved. Preservationmay involve filing them in sequence on a rolled up web of polyethylenefilm or the like so that any particular section which the photographshows to be of interest can be located and studied independently.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a diagrammatic plan view of theapparatus.

FIG. 2 is a diagrammatic side elevational view of certain components ofthe apparatus as they appear from the viewpoint indicated by line 22 ofFIG. 1.

FIG. 3 is a view on a larger scale showing the apparatus in section onthe line 3-3 of FIG. 1.

FIG. 4 is a fragmentary plan view of the microtome apparatus in plan,the apparatus being shown equipped with a vacuum tube for optionallywithdrawing sections which are to be discarded.

FIG. 5 is a view taken in section on the line 5-5 of FIG. 4.

FIG. 6 is a view of the microtome apparatus in plan, the structure hereshown being designed for use when the severed sections are to beretained and filed.

FIG. 7 is a view taken in section on the line 77 of FIG. 6.

FIG. 8 is an enlarged fragmentary detail view taken in section on theline 8*8 of FIG. 3.

FIG. 8A is a detail view taken in section on the line AA of FIG. 8.

FIG. 9 is a fragmentary plan view.

FIG. 10 is a fragmentary view in axial section through the indexingmechanism, showing the indexing table in its lowered and lockedposition.

FIG. 11 is a sectional view taken on the line 11--l1 of FIG. 10.

FIG. 12 is a view similar to FIG. 10 showing the table parts elevated todisengage the locking teeth for purposes of index- FIG. 13 is a detailview taken in section on the line 13-13 of FIG. 12.

FIG. 14 is a fragmentary view taken in section on the line 14-14 of FIG.12.

FIG. 15 is a fragmentary detail view partially in section and partiallyin elevation showing the ram which advances the work for a regulateddistance representing the thickness of the desired section.

FIG. 16 is a view taken in section on the line 16-16 of FIG. 15.

FIG. 17 is a view taken in section on the line 17-17 of FIG. 16.

FIG. 18 is a fragmentary detail view on an enlarged scale showing theengagement of the work-advancing rack with the pinion which effects thework advance.

FIG. 19 is a view illustrating in perspective and in relativelyseparated positions a water tank and its mounting on the housingfragmentarily shown.

FIG. 20 is a view of the mounted tank and housing in section.

FIG. 21 is a view of the tank in front elevation.

FIG. 22 is an enlarged detail view in perspective showing one of thespray nozzles.

FIG. 23 is a view of the nozzle in cross section.

FIG. 24 is an enlarged view partially in side elevation and partially insection showing the arrangement for mounting and operating the microtomeknife to cut the desired section.

FIG. 25 is a detail view taken in transverse section on the line 25-25of FIG. 24.

FIG. 26 is a view in horizontal section through the apparatus at a levelto expose the mechanism for advancing and retracting the hood whichconfines the work for spraying and exposes it for slicing and forphotography.

DETAILED DESCRIPTION The machine column housing 30 is generallycylindrical. Upon it is a rotary table on which the workpiece is mountedas hereinafter described to be angularly indexed step by step with 12,more or fewer, intervening periods of dwell. At station 1 (FIG. 1) athin section is removed from the face of the specimen. In the instantdevice, station 2 is an idle station at which no work is done. Atstation 3, and possibly stations 5 and 7, the exposed face of thespecimen is stained. At stations 4, 6, 8 and II, it is rinsed with wateror other cleansing liquid.

At station 9, any desired photograph is taken. At station 10, thesurface is photographed upon a very few frames of film in the motionpicture or animation camera 32. This is adjustable toward or from thecolumn 30 upon a track 33 which may project radially from the column asshown in FIG. 1 and may be bolted thereto as shown in FIG. 2. Details ofthe preferred construction are as follows:

Preliminary to its mounting in the machine, the specimen or workpiece 34is embedded in a block 36 of material which is susceptible to sectioningby the microtome knife. This block is keyed by ribs 38 to a mountingplate 40 attached to a ball 42 whereby it may be universally adjusted.The range of universal adjustment of the ball is small (rior inpractice). The ball may optionally have a lens (or merely an opening) 44which, in all ball positions, is open to the rear of the machine topermit the specimen to be backlighted if desired. The block of mountingmaterial 36 is usually translucent or transparent material, paraffin,nitrocellulose, or polyethylene glycol being preferred.

The ball 42 is seated in a concave bed or socket at 48 (FIG. 3) and isheld by a screw-pressed clamp 50 in the position to which it is adjustedby crank pins 54 and 56. These are respectively carried by nuts 58 and60 mounted on screw shafts 62 and 64, respectively, for manipulation byhandles 66 and 68 (FIGS. 8 and 9). The pins are engaged about 90 apartin the peripheral groove 69 of the ball. The arrangement is such thatthe work will pivot on one of the pins when it is being angularlyadjusted by manipulation of the other.

A hood or shield 70 is movable between advanced and retracted positions.It is shown retracted in FIGS. 1 and 3 so that it will not interferewith the movement of the microtome knife. It is also normally retractedduring photographing of the specimen to permit the illumination of thespecimen with light through the side of the translucent mountingmaterial, in addition to illumination from the front or the back (Lightsources are not shown). Ambient light may be used. The means foradvancing or retracting the hood or shield is best shown in FIG. 27 andwill later be described.

When the face of the specimen is being stained or washed, the shield 70is advanced to catch all overflow and confine the liquid and to deliverit to an appropriate hopper for return of the stain solution to itsreservoir and return of discharge water to a drain. The advancedposition of the shield is shown in dotted lines at the left in FIG. 3.Here it is in operative relation to the hopper 74, which receives thedrainage from the spout 76 in the bottom of the shield.

The specimen 34 and the block 36 in which it is mounted are subject tothree different types of movement in addition to its initial adjustmentby oscillation of its mounting ball. There is an angular table indexingmovement above mentioned; a vertical unlocking and relocking movementwhich accommodates the release of the indexing turntable from itsaccurately predetermined position and its return to a new positionequally accurately fixed; and finally, there is the controllable minuteradial advance of the specimen preliminary to the functioning of themicrotome knife in taking a fresh section from the face of the specimen.The thickness of the section will be determined by the extent of theadvance.

FEED ADVANCE OF SPECIMEN OVER KNIFE The advancing of the specimenpresents two problems: Extreme accuracy in increments of 1 micron(0.000039 inch); and wide range of 2 to 100 microns. The cycle of theindex table which is up, rotate, down, leads to a simple reliablesolution. The specimen is mounted on a 40 pitch lead screw with springloaded nut, resulting in a backlash-free arrangement. Keyed to the leadscrew is a 635 toothed drive gear. During the down stroke of the indextable this gear is placed in mesh with a rack, preferably made ofsynthetic resin, and held to a positive stop by an air cylinder. Nowherein this train is there play or backlash. Since one meter is 39.3 inches,1 micron is 0.0000393 inch and one tooth movement is l/40 X 6350.0000393. Consequently one tooth rotation advances the work 1 micron.By placing different blocks between the rack and a positive stop, thestroke of the rack can be controlled with great accuracy from 2 tomicrons the limits selected for our present machine.

This structure is best shown in FIGS. 3 and 15 to 18. The lead screw 146is engaged in a nut 144 which depends from the carriage 142, the latterbeing guided for movement on the supporting rails mounted on a bed 135on the turntable 84. Pre-loaded ball bushings 141 support the carriagefrom the shafts or rails 140. It is upon this carriage that the specimen34 and its mounting block are positioned. As above described, a concavesocket for ball seat 48 in which the ball 42 is initially adjusted is apart of the carriage 142.

To accomplish controlled rotation of the screw 146 for advancing thecarriage without backlash, the screw 146 carries and is driven by atoothed involute gear pinion 148 (FIG. 15) which may be engaged withrack as shown in FIG. 18 or may be raised free of the rack as shown inFIG. 17. In practice, the gear 148 has 635 teeth.

Movement of the pinion to and from engagement with the rack is effectedautomatically, since the rack 150 moves in a way 152 that is fixed tothe top deck 154 of the column, whereas the pinion 148 moves up and downwith the turntable in consequence of the movement of piston 98 abovedescribed.

The pinion 148 also rotates with the turntable. There is only oneposition of the turntable in which the pinion 148 will descend into meshwith rack 150 when the turntable descends. In all other positions, thepinion will be free of the rack either by virtue of the elevation of theturntable as shown in FIG. 17 or by virtue of the indexed movement ofthe turntable as shown, for example, in FIG. 3.

To rotate the pinion 148 and screw 146 to achieve controlled advance ofthe workpiece 34, there is a fluid operated ram cylinder having itspiston 162 connected with rack 150 as best shown in FIG. 15.Interchangeably disposed in the way 152 in the path of the rack is aspacer block or stop 164 (FIGS. 15 and 16). By substituting stopelements 164 of desired length, the movement of the rack may bepredetermined with precision. There is no backlash anywhere in the drivetrain. In practice, the arrangement enables the minutely controlledadvance of the surface of the workpiece 34 over the knife. In thisparticular device, the advance may be predetermined for a distancewithin a range of 2 to 100 microns so that the knife will cut from theexposed face of the workpiece a section of corresponding thickness.

INDEX A base 80 is mounted on a plate 82 which spans the column housing30. A turntable 84 is vertically reciprocable with reference to base 80and is guided thereby for rotation. FIG. 10 shows it in its lower fixedposition and FIG. 12 shows it elevated for indexing movement.

For locating with precision the indexed position of the turntable 84,mating radially toothed clutch rings 86 and 88 are provided (FIGS. 10,12, 13 and 14). These are not gears in fact but are known commerciallyas matched face splines. The ring 86 is fixed in a recess 90 of the base80. The ring 88 is disposed in a relatively inverted position in acorresponding recess 92 of the turntable 84. The teeth 94 are formedwith precision and are not comparable to gear teeth since there is notransmission of motion. In the elevated position of the turntable shownin FIG. 12, none of the teeth are in engagement. In the lower positionshown in FIG. 10, all of the teeth are in engagement.

For raising and lowering the turntable and the specimenmounting partscarried thereby, a fluid operated double-acting ram is preferablyemployed. Fixed in the base is a cylinder 96. The piston 98 reciprocabletherein is mounted on a sleeve 100 which is both rotatable and axiallymovable with respect to the cylinder 96. The duct 102 communicates fluidpressure to the cylinder below the piston flange 98. The duct 104communicates with the cylinder base above the piston. The piston sleeve100 is keyed at 106 to the headed shaft 108 which supports the turntable84. When the piston and shaft and turntable are elevated as shown inFIG. 12, the turntable may be indexed because the teeth 94 of the rings86 and 88 are disengaged. In the lowered position of the parts shown inFIG. 10, no indexing movement is possible, the teeth 94 being engaged.

The indexing of the turntable is achieved by means of the rack piston110 which moves back and forth in the cylinder 112 under fluid pressure(preferably pneumatic) communicated to it through the pressure line 114or 116 subject to the control of a multiple valve 118 in the supply andreturn lines 120, 122 (FIG. 11). The teeth 124 formed in the side of therack piston 110 mesh with the gear 126 which is keyed to the aforesaidsleeve 100. A stop 125 of accurately predetermined length projects fromone end of cylinder 112 into the path of movement of the rack piston 110to predetermine with precision the movement of which the rack pistonwill be capable when subjected to pressure through the line 116.

In the specific device illustrated in which there are 12 stations atwhich dwell occurs, the arrangement is such that each operation of thepiston 110 will index the elevated turntable 84 for 30. Thereupon theram piston 96 will descend to engage the toothed rings 86 and 88 for aprecise determination of the indexed position. In the lower position ofthe piston, the teeth 130 on the flange 132 of the piston sleeve 100will be disengaged from the complementary teeth 134 on the under surfaceof the gear 126, as shown in FIG. 10. This will release the rotativeparts from the rack and pinion 126. The pinion automatically returns toits original position without affecting the rotative parts.

After 12 successive indexed advances and dwells, the turntable will havebeen restored to its original position at station 1 to place the workspecimen in registry with the microtome knife.

THE KNIFE MOUNTING AND ACTUATION The disposable knife 170 is positionedin any desired manner (as by clamp wedge 172) on a verticallyreciprocable operating head 174 from which its cutting edge 176 projectsslightly (FIG. 7) to sever a very thin section 180 from the mountingblock 36 and the specimen 34 embedded therein. The angle of the knife170 is pivotally adjustable on the knife carrier 174 on an axis whichpreferably coincides with the cutting edge 176 of the knife. The angleof the knife is adjusted by providing the knife supporting head 174 witha slotted cylindrical surface 177 coaxial with the knife at 176 and uponwhich the complementary surface 179 of the knife supporting member 175is held by bolts 181 projecting through the slots as best shown in FIG.5.

If the severed material is to be saved, the section 180 is guided onto atable surface 182 on the head 174 and is desirably confined beneath adecurler bar 184 as shown in FIG. 7. If it is not to be saved, it issubject to the suction of a vacuum nozzle 186 and pipe 187 as shown inFIGS. 4 and 5. The air flow tends to breakit into small fragments asshown at 188 of FIG. 5.

The knife supporting head 174 is guided for movement on a verticallyreciprocable post 190 (FIGS. 3 and 24) for which the column housing 30provides a bearing at 192. The bar 190 supports a cross yoke 194 havingconnected to each of its ends a piston rod 196 of one of a pair of rams198 suspended from brackets 200 which project outwardly from the column30 (FIG. 3). When pressure is applied to the rams 198 below the pistons196, the pistons will rise in the rams to force the bar 190 and the head174 upwardly to effect the sectioning operation shown in FIG. 7.

Since great accuracy is required, the column housing is provided withways 201 (FIG. 25) engaged by socketed bearing elements 202. Preferablythe bearing elements are simply disks which ride on the respective waysand are carried by a bracket 204 attached to the posts 190. At one sideof the post, the bracket is provided with a pin 206 biased by spring 208against one of the bearing disks 202. At the other side of the post, thethrust screw 210 is threadedly adjustable in bracket 204 into engagementwith the other of the bearing disks. For slight angular adjustment ofthe position of the post and the knife carried thereby, it is onlynecessary to rotate the screw 210 inwardly or outwardly as required. Thespring biased pin 206 accommodates this movement so that adjustment ofonly one screw is necessary.

STAINING AND WASHING After a very thin section has been cut with knifeedge 176 from the workpiece 34 and the embedding block 36, the exposedface of the workpiece is treated with a stain or stains appropriate tobring out the feature or features under investigation. The first suchstain is applied by jetting it from a nozzle 212 (FIG. 2) against theworkpiece when the workpiece dwells at station 3 (station 2 is not usedin this particular device). FIGS. 22 and 23 show a typical nozzle 212.It is an elongated device preferably made of a silicone resin tominimize adhesion of chemicals to it. It has a coupling at 214 for apipe 254 which supplies the stain from a pressurizing pump as hereafterdescribed.

The equipment is made adaptable enough to meet all requirements bydetachably securing pods 216 and 217 to the housing or column 30 atdesired angularly spaced locations. This is conveniently done as shownin FIGS. 2, 3, l9 and 20. The pods 216 have receptacles 220 for stain,and motordriven pumps for delivering the stain through the nozzles 212.The pods 217 operate under conventional water pressure and hence requireno pumps. Desirably their receptacles are similar to the tanks of pods216 and the design is such that these may contain water softener orsolvents to be injected into the water supplied from the city system.Both sets of pods are mounted similarly on the column.

Each pod is provided at its rear with a generally horizontal elongatedinverted channel-shaped hook 222, above which there is an aperturedangle flange 224. The manifold 226 on the housing 30 has a downwardlyprojecting peg 228 receivable into the aperture of the angle fitting224. It has length enough to maintain engagement between the parts whenthe pod is lifted so that the flange of channel 222 can go into the slot230 provided in the bracket 234 on the side wall of the housing (FIGS.19 and 20).

A typical construction of pods 216 is shown in FIGS. 2 and 3, each suchpod including a reservoir 220. A motor 221 drives a pump 223 whichwithdraws stain from the reservoir 220 and delivers it through the pipe254 to the nozzle 212. The nozzle is supported by a bracket arm 225. Asalready explained, any surplus stain draining from the workpiece isintercepted by the shield 70, the spout 76 of which returns the stainthrough hopper 74 to the registering receptacle 220 from which it waspumped.

In order to cover the entire surface of the work, the nozzles 212 areprovided with numerous delivery orifices 262 spaced lengthwise of thenozzle as shown in FIGS. 22 and 23. The plugs 263 and 264 can beadjusted by tool 266 lengthwise of the nozzle passage 268 to control thenumber of discharge orifices 262 which are left available for jettingliquid against the work according to the width of the block face whichis to be stained.

Pods 217 used for rinsing do not require motors or pumps or specialnozzles. Their nozzles 215 are supplied with water under pressure fromcity lines, the water being conveyed to the pod by the hoses 245.Subject to the control of valves 247 (FIG. 19) the water passes througha tube 250 into an aspirator 244 which entrains any desired liquid 241from the tank 220, such liquid passing through the pipe 240 and the flowwater sight glass 238 and the pipe 242 to the aspirator 244. The mixturethen passes through pipe 246 and sight glass 248 and through the tube251 to the nozzle 215 (FIGS. 2 and 21).

rnnna-v nAnn To keep the tray or pan 256 clean, it is desirable that itbe flushed. This is conveniently done by water discharged into the pan256 through a flushing pipe 270 (FIG. 3). The issuing rinse water isheld close to the surface of the pan by means of a baffle 272. InpraCtice, the rinse water is permitted to flow continuously through thesupply pipe 270 and out the drain pipe 258 as long as the device is inoperation.

REGULATION OF POSITION OF THE SHIELD Reference has been made to the factthat the work is partially enclosed within a shield 70 when either stainor rinse water is being discharged onto the work. The shield is shown ina retracted position in FIGS. 1, 2, 9 and 26. FIG. 3 also shows theshield retracted at the right in FIG. 3 but shows it in dotted lines inits advanced position at the left in FIG. 3. It will be understood thatthe hood is advanced at all times during spraying and rinsing and isretracted during the sectioning and, preferably, also duringphotography. In its advanced position, it either encloses the work faceor is only about one-tenth of an inch behind the work face. Duringsectioning or photography, the shield is withdrawn so that its leadingpart is perhaps 3 inches more or less behind the work face.

As is best shown in FIG. 8, we provide guide rollers 274 upon which theshield 70 moves for advance and retraction. The shield 70 is advanced bythe bias of tension springs 276 (FIG. 26). As shown, these springs areanchored at the right and connected to the shield 70 by means of pins278.

Fixed to the top deck 154 is a cam 280 (FIGS. 3 and 26) which hasrelatively high points at 282 and 284. A head chain 286 connected at 288with the shield 70 passes about a segmental pulley 290 which is mountedfor pivotal movement on a rock shaft 292 which carries a crank 294supporting a cam follower 296 engaged with the inner margin of the cam280. The bias of the tension springs 276 holds the cam follower tightlyagainst the cam. When the cam follower rides over the high points 282 or284 of the cam, the shield 70 is retracted against the bias of springs276. As the cam follower leaves the high points of the cam or passescompletely from the cam the shield is retracted by its biasing springsto avoid interference with the sectioning knife, or to admit lightlaterally to the translucent block 36 in which the workpiece is mounted,as shown in FIG. 3.

By reason of the arrangement whereby all desired operations are achievedduring the rotative intermittent or step by step angular advance of thework upon a turntable, the device is highly versatile and can beadjusted to permit any desired time for staining or rinsing, for drying,for photographing, and for the microtome severance of successivesections. Once the timing is fixed, the desired values of the operationwill repeat themselves cyclically indefinitely without attention.

It will be understood, of course, that practically all of theseoperations are controlled in a conventional manner by a timer, notshown. The timer will turn the stain jetting pumps and rinse jets on andoff in proper sequence and for desired periods; will actuate thecameras; will operate the microtome knife forth and back when the workis registered therewith; and will actuate the table indexing mechanism,indirectly retracting or advancing the shield as dictated by the cam.

The machine produces more accurate results than any previously availablemachine because, at the time the section face is photographed or viewed,it is still supported. For the same reason, the knife will take athinner section than has heretofore been practical.

Using known integrating equipment, it is possible to compare the colorof various portions of the work to determine such factors as therelative proportion of voids to solids, and the area and number ofcells.

We claim:

1. A microtome device comprising, in combination, a bearing establishinga center of rotation, a mounting for a workpiece having a radiallyexposed face, means for sectioning the workpiece and including amicrotome knife and mechanism for actuation thereof; camera means; saidsectioning means and camera means being angularly spaced about saidcenter of rotation and means for presenting said exposed facesuccessively to said first and second means by effecting relativeindexing rotation about said center between the workpiece and the firstand second means, the means with respect to which the workpiece hasrelative indexing rotation including a third means comprising a nozzlefor directing stain against the exposed sectioned face of the workpiecein advance of presentation of said exposed face to said camera means.

2. A combination according to claim 1 in which the first, second andthird means have mounts upon which they are fixed, and a turntablesupported for rotation about said center is provided with said mountingfor said workpiece.

3. A combination according to claim 2 in which the bearing establishingthe center of rotation is on a column, the column and the table havingmatched-face gears axially engageable and disengageable, and means forperiodically elevating the table to disengage said gears and forthereafter indexing the table, and means for lowering the-table toreengage said gears when the table is in positions to register theworkpiece respectively with the first, second and third said means.

4. A combination according to claim 1 including stain propelling meansleading to the nozzle and in which said turntable includes a shieldhaving means mounting it for forth and back radial adjustment betweenretracted and forward positions, said shield having portions adapted ina forward position to at least largely embrace the workpiece to retainspray directed thereon by said nozzle, the stain propelling meansincluding a stain tank, a motor-driven pump, and hose connections fordischarging stain from the tank through the nozzle, said shield having adischarge spout for the delivery of collected liquid, and said tankhaving a receiving hopper which registers with said spout to receivecollected liquid in the position of the turntable in which the workregisters with the nozzle.

5. A combination according to claim 4 in which cam an cam follower meansrespectively interacting in the course of turntable rotation havedriving connections for advance and retraction of said shield and areadapted to advance the shield before the propelling means is operativeand to retract the shield before the camera means and the sectioningmeans are operative.

6. A microtome device comprising, in combination, a bearing establishinga center of rotation, a mounting for a workpiece having a radiallyexposed face, means for sectioning the workpiece and including amicrotome knife and mechanism for actuation thereof; camera means; saidsectioning means and camera means being angularly spaced about saidcenter of rotation and means for presenting said exposed facesuccessively to said first and second means by effecting relativeindexing rotation about said center between the workpiece and the firstand second means, the mounting for the workpiece including a slidemovable along a radius of said center, and means for periodically movingsaid slide radially past said knife for an amount equal to the thicknessof the section to be cut by said knife in further combination with aturntable having a way upon which said slide is movable, means forindexing the turntable, means for locking the turntable in at least oneindexed position, means for axially elevating the turntable from anormal lower position to a raised position to disengage said lockingmeans in advance of indexing movement from said one position, a leadscrew on the turntable, a nut on the slide which meshes with the screw,means for rotating the screw and including a drive gear thereon, a rackhaving a way provided by the turntable, said drive gear meshing withsaid rack in the lower position of the turntable and being elevated freethereof when the turntable is raised, and means for advancing the rackfor a predetermined distance along the last mentioned way for effectingrotation of said lead screw to advance said slide and the work mountedthereon.

7. A microtome device comprising, in combination, a bearing establishinga center of rotation, a mounting for a workpiece having a radiallyexposed face, means for sectioning the workpiece and including amicrotome knife and mechanism for actuation thereof; camera means; saidsectioning means and camera means being angularly spaced about saidcenter of rotation and means for presenting said exposed facesuccessively to said first and second means by efiecting relativeindexing rotation about said center between the workpiece and the firstand second means, the mounting for the workpiece including a ball towhich the workpiece is fixed, and a socket in which said ball isadjustably mounted, said ball having an opening for the backlighting ofthe workpiece, and a translucent, sectionable material connecting theworkpiece with the ball.

8. A combination according to claim 7 in which a lens controlsdiffraction of light through said opening.

9. A microtome device comprising, in combination, a bearing establishinga center of rotation, a mounting for a workpiece having a radiallyexposed face, means for sectioning the workpiece and including amicrotome knife and mechanism for actuation thereof; camera means; saidsectioning means and camera means being angularly spaced about saidcenter of rotation and means for presenting said exposed facesuccessively to said first and second means by effecting relativeindexing rotation about said center between the workpiece and the firstand second means, said column being provided at angularly spacedintervals with pods, each of which includes a tank of liquid and a spraynozzle with which the workpiece will register in successive indexedpositions of the turntable, and means for jetting liquid from arespective pod through its spray nozzle and upon the sectioned face ofthe workpiece registering therewith.

10. A device according to claim 9 in which the respective pod is adaptedto jet stain upon the face of the workpiece and includes a stainpropelling pump having an output connected with said nozzle, said lastmentioned pod being so positioned on the column that the workpiece willregister therewith after being sectioned and before the sectioned faceregisters with the camera.

11. A combination according to claim 9 in which the pod and column haverelatively separable elements for the detachable mounting of the podupon the column.

1. A microtome device comprising, in combination, a bearing establishinga center of rotation, a mounting for a workpiece having a radiallyexposed face, means for sectioning the workpiece and including amicrotome knife and mechanism for actuation thereof; camera means; saidsectioning means and camera means being angularly spaced about saidcenter of rotation and means for presenting said exposed facesuccessively to said first and second means by effecting relativeindexing rotation about said center between the workpiece and the firstand second means, the means with respect to which the workpiece hasrelative indexing rotation including a third means comprising a nozzlefor directing stain against the exposed sectioned face of the workpiecein advance of presentation of said exposed face to said camera means. 2.A combination according to claim 1 in which the first, second and thirdmeans have mounts upon which they are fixed, and a turntable supportedfor rotation about said center is provided with said mounting for saidworkpiece.
 3. A combination according to claim 2 in which the bearingestablishing the center of rotation is on a column, the column and thetable having matched-face gears axially engageable and disengageable,and means for periodically elevating the table to disengage said gearsand for thereafter indexing the table, and means for lowering the tableto re-engage said gears when the table is in positions to register theworkpiece respectively with the first, second and third said means.
 4. Acombination according to claim 1 including stain propelling meansleading to the nozzle and in which said turntable includes a shieldhaving means mounting it for forth and back radial adjustment betweenretracted and forward positions, said shield having portions adapted ina forward position to at least largely embrace the workpiece to retainspray directed thereon by said nozzle, the stain propelling meansincluding a stain tank, a motor-driven pump, and hose connections fordischarging stain from the tank through the nozzle, said shield having adischarge spout for the delivery of collected liquid, and said tankhaving a receiving hopper which registers with said spout to receivecollected liquid in the position of the turntable in which the workregisters with the nozzle.
 5. A combination according to claim 4 inwhich cam and cam follower means respectively interacting in the courseof turntable rotation have driving connections for advance andretraction of said shield and are adapted to advance the shield beforethe propelling means is operative and to retract the shield before thecamera means and the sectioning means are operative.
 6. A microtomedevice comprising, in combination, a bearing establishing a center ofrotation, a mounting for a workpiece having a radially exposed face,means for sectioning the workpiece and including a microtome knife andmechanism for actuation thereof; camera means; said sectioning means andcamera means being angularly spaced about said center of rotation andmeans for presenting said exposed face successively to said first andsecond means by effecting relative indexing rotation about said centerbetween the workpiece and the first and second means, the mounting forthe workpiece including a slide movable along a radius of said center,and means for periodically moving said slide radially past said knifefor an amount equal to the thickness of the section to be cut by saidknife in further combination with a turntable having a way upon whichsaid slide is movable, means for indexing the turntable, means forlocking the turntable in at least one indexed position, means foraxially elevating the turntable from a normal lower position to a raisedposition to disengage said locking means in advance of indexing movementfrom said one position, a lead screw on the turntable, a nut on theslide which meshes with the screw, means for rotating the screw andincluding a drive gear thereon, a rack having a way provided by theturntable, said drive gear meshing with said rack in the lower positionof the turntable and being elevated free thereof when the turntable israised, and means for advancing the rack for a predetermined distancealong the last mentioned way for effecting rotation of said lead screwto advance said slide and the work mounted thereon.
 7. A microtomedevice comprising, in combination, a bearing establishing a center ofrotation, a mounting for a workpiece having a radially exposed face,means for sectioning the workpiece and including a microtome knife andmechanism for actuation thereof; camera means; said sectioning means andcamera means being angularly spaced about said center of rotation andmeans for presenting said exposed face successively to said first andsecond means by effecting relative indexing rotation about said centerbetween the workpiece and the first and second means, the mounting forthe workpiece including a ball to which the workpiece is fixed, and asocket in which said ball is adjustably mounted, said ball having anopening for the backlighting of the workpiece, and a translucent,sectionable material connecting the workpiece with the ball.
 8. Acombination according to claim 7 in which a lens controls diffraction oflight through said opening.
 9. A microtome device comprising, incombination, a bearing establishing a center of rotation, a mounting fora workpiece having a radially exposed face, means for sectioning theworkpiece and including a microtome knife and mechanism for actuationthereof; camera means; said sectioning means and camera means beingangularly spaced about said center of rotation and means for presentingsaid exposed face successively to said first and second means byeffecting relative indexing rotation about said center between theworkpiece and the first and second means, said column being provided atangularly spaced intervals with pods, each of which includes a tank ofliquid and a spray nozzle with which the workpiece will register insuccessive indexed positiOns of the turntable, and means for jettingliquid from a respective pod through its spray nozzle and upon thesectioned face of the workpiece registering therewith.
 10. A deviceaccording to claim 9 in which the respective pod is adapted to jet stainupon the face of the workpiece and includes a stain propelling pumphaving an output connected with said nozzle, said last mentioned podbeing so positioned on the column that the workpiece will registertherewith after being sectioned and before the sectioned face registerswith the camera.
 11. A combination according to claim 9 in which the podand column have relatively separable elements for the detachablemounting of the pod upon the column.